21033155 has 32 divisors (see below), whose sum is σ = 30965760. Its totient is φ = 13495680.

The previous prime is 21033151. The next prime is 21033161. The reversal of 21033155 is 55133012.

It is not a de Polignac number, because 21033155 - 2² = 21033151 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21033151) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 15806 + ... + 17084.

It is an arithmetic number, because the mean of its divisors is an integer number (967680).

Almost surely, 2^21033155 is an apocalyptic number.

21033155 is a deficient number, since it is larger than the sum of its proper divisors (9932605).

21033155 is a wasteful number, since it uses less digits than its factorization.

21033155 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1331.

The product of its (nonzero) digits is 450, while the sum is 20.

The square root of 21033155 is about 4586.1917753186. The cubic root of 21033155 is about 276.0375351528.

Adding to 21033155 its reverse (55133012), we get a palindrome (76166167).

The spelling of 21033155 in words is "twenty-one million, thirty-three thousand, one hundred fifty-five".